Water Quality Loading: Trends in the Northeastern Corridor of US During the 20th Century

Water quality in surface waters is influenced by watershed climate, hydrology, land cover and land use. Inputs from anthropogenic sources, such as fertilizers, wastewater and livestock, can greatly degrade water quality as they are transferred into surface water bodies. It is important to quantify the rate and severity of this transformation in order to minimize water quality damages to water resources. Additionally, throughout the 20th century, land use practices have constantly shifted with technological advancements and increases in population. Export coefficient models are useful regional scale models, which can address non-point pollution sources; however, such models only address land use practices without regard for other inputs to the hydrologic system. While physical models can model the relationships between the hydrologic system, human activities and water quality, such models are complex to develop and only apply to localized areas. Our primary goal is to quantify and characterize the trends in total nitrogen, total phosphorus and BOD loading into surface waters in the Northeast Corridor of the US from 1920-2000. The models combine features of export coefficient models and physical models using streamflow, climate, land use and anthropogenic inputs. Models are developed for 26 watersheds across the Northeast Corridor, which have over 10 years of water quality data. These models are representative of a wide range of land use types and thus may be applied to HUC 8 watersheds within the region. The resulting models describe how land use practices and the hydrologic system have affected water quality for this time period. Cross validation methods are employed to test and evaluate the resulting models.